Garage Door Opener The Saga Continues

I posted earlier about my 2 garage doors failing the safety reversal test and got some good insight from replies but still have questions. As I mentioned one opener is brand new;the other about 15 years old so I conclude the openers are not the problem and that it must be something with the doors.(I did increase the downward force and all that did was arch the door.So I turned it back)

From what I've read the next likely cause is the springs. So I tighten them eventually as far as they can go and still no change. I then check the springs by disconnecting the opener trolley and open the doors to a height of about 3 feet and they remain open.

Now I did notice on the door with the old opener the piece that holds one of the bottommost rollers is missing so that roller is struggling to move. I understand the issues involved with the spring cable being attached to it.
So 3 questions, first can roller cause the door to fail the test? Second what is the name of that piece that fits on the end of the roller to hold it in the hinge?
And finally what else could cause the doors to fail the safety test?
I'm close to calling a pro but sure hate to pay something simple

If the door binds in any way, that needs to be fixed. A good hardware store or a place that specializes in installing them would likely have the repair parts. All of the brackets, rollers, and hinges need to be in proper working condition. You should be able to smoothly raise and lower the door with the opener disconnected by hand. If all of that works, then there is no good reason I can think of for the opener to baulk at working.